a more forgiving array behavior
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4 changed files with 48 additions and 10 deletions
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@ -29,7 +29,7 @@ Other aspects were not so important to us:
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As of February 2015, the following updates were made to the library
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- *Changed:* In the generic class `basic_json`, all JSON value types (array, object, string, bool, integer number, and floating-point) are now **templated**. That is, you can choose whether you like a `std::list` for your arrays or an `std::unordered_map` for your objects. The specialization `json` sets some reasonable defaults.
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- *Changed:* The library now consists of a single header, called `json.hpp`. Consequently, build systems such as Automake or CMake are not any longer required.
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- *Changed:* The library now consists of a **single header**, called `json.hpp`. Consequently, build systems such as Automake or CMake are not any longer required.
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- *Changed:* The **deserialization** is now supported by a lexer generated with [re2c](http://re2c.org) from file [`src/json.hpp.re2c`](https://github.com/nlohmann/json/blob/master/src/json.hpp.re2c). As a result, we follow the JSON specification more strictly. Note neither the tool re2c nor its input are required to use the class.
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- *Added:* The library now satisfies the [**ReversibleContainer**](http://en.cppreference.com/w/cpp/concept/ReversibleContainer) requirement. It hence provides four different iterators (`iterator`, `const_iterator`, `reverse_iterator`, and `const_reverse_iterator`), comparison functions, `swap()`, `size()`, `max_size()`, and `empty()` member functions.
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- *Added*: The class uses **user-defined allocators** which default to `std::allocator`, but can be templated via parameter `Allocator`.
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@ -184,7 +184,7 @@ These operators work for any subclasses of `std::istream` or `std::ostream`.
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### STL-like access
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We designed the JSON class to behave just like an STL container:
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We designed the JSON class to behave just like an STL container. In fact, it satisfies the [**ReversibleContainer**](http://en.cppreference.com/w/cpp/concept/ReversibleContainer) requirement.
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```cpp
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// create an array using push_back
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18
src/json.hpp
18
src/json.hpp
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@ -712,12 +712,26 @@ class basic_json
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/// access specified element
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inline reference operator[](size_type pos)
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{
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// at only works for arrays
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// implicitly convert null to object
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if (m_type == value_t::null)
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{
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m_type = value_t::array;
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Allocator<array_t> alloc;
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m_value.array = alloc.allocate(1);
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alloc.construct(m_value.array);
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}
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// [] only works for arrays
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if (m_type != value_t::array)
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{
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throw std::runtime_error("cannot use [] with " + type_name());
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}
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for (size_t i = m_value.array->size(); i <= pos; ++i)
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{
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m_value.array->push_back(basic_json());
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}
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return m_value.array->operator[](pos);
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}
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@ -769,7 +783,7 @@ class basic_json
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alloc.construct(m_value.object);
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}
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// at only works for objects
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// [] only works for objects
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if (m_type != value_t::object)
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{
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throw std::runtime_error("cannot use [] with " + type_name());
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@ -712,12 +712,26 @@ class basic_json
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/// access specified element
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inline reference operator[](size_type pos)
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{
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// at only works for arrays
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// implicitly convert null to object
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if (m_type == value_t::null)
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{
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m_type = value_t::array;
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Allocator<array_t> alloc;
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m_value.array = alloc.allocate(1);
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alloc.construct(m_value.array);
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}
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// [] only works for arrays
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if (m_type != value_t::array)
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{
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throw std::runtime_error("cannot use [] with " + type_name());
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}
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for (size_t i = m_value.array->size(); i <= pos; ++i)
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{
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m_value.array->push_back(basic_json());
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}
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return m_value.array->operator[](pos);
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}
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@ -769,7 +783,7 @@ class basic_json
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alloc.construct(m_value.object);
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}
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// at only works for objects
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// [] only works for objects
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if (m_type != value_t::object)
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{
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throw std::runtime_error("cannot use [] with " + type_name());
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@ -2032,13 +2032,23 @@ TEST_CASE("element access")
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SECTION("access on non-array type")
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{
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SECTION("null")
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{
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SECTION("standard tests")
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{
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json j_nonarray(json::value_t::null);
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const json j_nonarray_const(j_nonarray);
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CHECK_THROWS_AS(j_nonarray[0], std::runtime_error);
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CHECK_NOTHROW(j_nonarray[0]);
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CHECK_THROWS_AS(j_nonarray_const[0], std::runtime_error);
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}
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SECTION("implicit transformation to properly filled array")
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{
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json j_nonarray;
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j_nonarray[3] = 42;
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CHECK(j_nonarray == json({nullptr, nullptr, nullptr, 42}));
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}
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}
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SECTION("boolean")
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{
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json j_nonarray(json::value_t::boolean);
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